CHANNEL EXTENSION CODING FOR MULTI-CHANNEL SOURCE
First Claim
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1. A method of reconstructing multi-channel audio from a compressed bitstream, the method comprising:
- receiving the compressed bitstream, the compressed bitstream containing a plurality of coded channels and power correlation parameters, the number of coded channels being fewer than a number of physical channels of the multi-channel audio, the power correlation parameters characterizing a full power correlation matrix;
decoding a vector of coded audio channel coefficients and power correlation parameters from the received bitstream for a frequency band;
forming a virtual audio channel coefficients vector for the frequency band comprising the decoded vector of coded audio channel coefficients and coefficients of decorrelated versions of the coded audio channels;
determining the full power correlation matrix for the frequency band from the power correlation parameters;
constructing a linear transform for multi-channel audio reconstruction relating the virtual audio channel coefficients vector to a reconstructed multi-channel audio coefficients vector;
applying the linear transform to the virtual audio channel coefficients vector to produce the reconstructed multi-channel audio coefficients vector; and
applying an inverse time-frequency transform to the reconstructed multi-channel audio coefficients vector to reproduce the multi-channel audio.
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Abstract
A multi-channel audio decoder reconstructs multi-channel audio of more than two physical channels from a reduced set of coded channels based on correlation parameters that specify a full power cross-correlation matrix of the physical channels, or merely preserve a partial correlation matrix (such as power of the physical channels, and some subset of cross-correlations between the physical channels, or cross-correlations of the physical channels with coded or virtual channels).
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Citations
20 Claims
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1. A method of reconstructing multi-channel audio from a compressed bitstream, the method comprising:
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receiving the compressed bitstream, the compressed bitstream containing a plurality of coded channels and power correlation parameters, the number of coded channels being fewer than a number of physical channels of the multi-channel audio, the power correlation parameters characterizing a full power correlation matrix; decoding a vector of coded audio channel coefficients and power correlation parameters from the received bitstream for a frequency band; forming a virtual audio channel coefficients vector for the frequency band comprising the decoded vector of coded audio channel coefficients and coefficients of decorrelated versions of the coded audio channels; determining the full power correlation matrix for the frequency band from the power correlation parameters; constructing a linear transform for multi-channel audio reconstruction relating the virtual audio channel coefficients vector to a reconstructed multi-channel audio coefficients vector; applying the linear transform to the virtual audio channel coefficients vector to produce the reconstructed multi-channel audio coefficients vector; and applying an inverse time-frequency transform to the reconstructed multi-channel audio coefficients vector to reproduce the multi-channel audio. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of reconstructing multi-channel audio from a compressed bitstream, the method comprising:
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receiving the compressed bitstream, the compressed bitstream containing a plurality of coded channels and power correlation parameters, the number of coded channels being fewer than a number of physical channels of the multi-channel audio, the power correlation parameters characterizing at least a partial power correlation matrix; decoding a vector of coded audio channel coefficients and power correlation parameters from the received bitstream for a frequency band; producing a vector of coefficient of a plurality of virtual audio channels for the frequency band as a linear transform of the coded audio channel coefficients vector; producing a decorrelated version of the virtual audio channel coefficients vector for the frequency band; calculating weighting factors for preserving power of the physical channels and cross-correlation between the physical channels; reconstructing a multi-channel audio coefficients vector for the frequency band as a sum of products of the weighting factors and the versions of the virtual audio channel coefficients vector; and applying an inverse time-frequency transform to the reconstructed multi-channel audio coefficients vector to reproduce the multi-channel audio. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method of reproducing multi-channel audio from a compressed bitstream, the method comprising:
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receiving the compressed bitstream, the compressed bitstream containing a plurality of coded channels and power correlation parameters, the number of coded channels being fewer than a number of physical channels of the multi-channel audio, the power correlation parameters characterizing at least a partial power correlation matrix; decoding a vector of coded audio channel coefficients and power correlation parameters from the received bitstream for a frequency band; producing a virtual audio channel coefficients vector corresponding to a plurality of virtual channels for the frequency band based on the coded audio channel coefficients vector; deriving reconstruction parameters from the power correlation parameters that preserve at least partially a power cross-correlation matrix of the physical channels; reconstructing a multi-channel audio coefficients vector for the frequency band as a function of the virtual audio channel coefficients and reconstruction parameters; and applying an inverse time-frequency transform to the reconstructed multi-channel audio coefficients vector to reproduce the multi-channel audio. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification